1. Field of the Invention
The present invention relates to a Multicast and Broadcast Service (MBS) in a wireless communication system. More particularly, the present invention relates to a method and an apparatus for recognizing an MBS region by an MBS DaisyChain mechanism in a broadband wireless communication system.
2. Description of the Related Art
In a 4th Generation (4G) communication system, which is the next generation communication system, research for providing users with services having various Quality of Services (QoS) using a transmission speed of about 100 Mbps are under active progress. More particularly, research for supporting a high speed service in the form of guaranteeing a Broadband Wireless Access (BWA) communication system such as a wireless Local Area Network (LAN) system and a wireless Metropolitan Area Network (MAN) system, mobility and QoS are under active progress. Also, for a representative communication system, there exists the Institute of Electrical and Electronics Engineers (IEEE) 802.16 system.
The IEEE 802.16-based broadband wireless communication system provides the Internet, Voice over Internet Protocol (VoIP), and a non-real time streaming service as a primary service. Also, recently, a Multicast Broadcast Service (MBS), which is a real-time broadcast service, has emerged as a new service. More particularly, in the MBS, a plurality of base stations transmit broadcast data bursts which use the same coding scheme via the same frequency and time resources, so that even a terminal located in a cell edge may obtain a macro diversity effect through Radio Frequency (RF) combining.
FIG. 1 illustrates a DownLink (DL) frame structure for providing an MBS in a conventional broadband wireless communication system.
As illustrated in FIG. 1, to support the macro diversity, a plurality of base stations define a portion of a frame as an MBS region 150, and transmit MBS data bursts 111, 113 and 115 via the MBS region 150. Here, the location of the MBS region is transferred via a DL MAP message 103. The DL MAP message 103 includes MBS_MAP_IE 105. The MBS_MAP_IE 105 includes the location information of an MBS MAP message 107 including assignment information of the MBS data bursts 111 to 115. Accordingly, a terminal recognizes the location of the MBS MAP message 107 through the DL MAP message 103, and recognizes the location of an MBS region 150 and the location and coding information of the MBS data bursts 111 to 115 inside the MBS region 150 through the MBS MAP message 107, thereby receiving the MBS data bursts 111 to 115.
In other words, to receive MBS data bursts 111 to 115, a relevant terminal decodes MBS_MAP_IE 105 included in the DL MAP message 103, decodes the MBS MAP message 107 using the decoded MBS_MAP_IE 105, and recognizes the location and coding information of the MBS data bursts 111 to 115 using MBS_DATA_IE 109 included in the MBS MAP message 107.
When various kinds of MBS MAP information and MBS MAP messages are transmitted every frame to decode the MBS data bursts 111 to 115, overhead may be generated. To reduce this overhead, an MBS DaisyChain mechanism may be used. The MBS DaisyChain mechanism may decode only the MBS MAP message 107 to receive an MBS data burst without decoding the DL MAP message 103.
However, on the assumption that an MBS data burst location and the starting point of the MBS region match each other, when, in the MBS DaisyChain mechanism, an MBS region through which transmission is made according to the transmission periods of MBS data bursts and an MBS MAP message for different MBS data bursts exist simultaneously, MBS regions do not match with each other at a terminal. Accordingly, the MBS DaisyChain mechanism may not properly receive MBS data bursts.